Snap to first label from left side

[eliotfowler]

The slider won't snap to the first label from the left side. It always snaps back to the previous one.

To reproduce:

• Open the demo
• Go to the snap to labels example
• Drag the slider to 99% or just to the left of the 'A'
• It should snap to the 'A' but it snaps to the 'E' instead